The present invention relates generally to methods for closed-loop control of technical processes, and more specifically to a closed-loop control method for control of technical processes that use multiple controllers, whereby the performance characteristics of these processes are clearly dependent on the working point that is active at the time. Working points can be defined by several variables, so-called working-point parameters. These parameters are not correlated to the directly controlled variable and are specified as fixed or variable parameters. Examples of such technical processes are controlling tape tension for reel-to-reel drives, controlling electrodes in arc furnaces, controlling turbine-driven generators, or controlling cement-production processes. To achieve invariably good control results in the different working points, then the closed-loop control device must be specifically adapted to the working point that is active at the time.
One could provide a specifically adapted controller for each individual working point and work only with this controller in the prevailing working-point environment. However, to cover the working range of interest, this would require an often unreasonably high number of individual controllers. Furthermore, the problem exists as to how to transition from one controller to the next controller in an uninterrupted and gradual manner.
The present invention is directed to the problem of developing a method that will allow a smooth, gradual transition from one controller to the other, when there are changes in working points, while simultaneously reducing the number of required controllers.